<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
</head>

<body>
	<script>
		let x = 1;
		debugger
		function A(y) {
			let x = 2;
			debugger
			function B(z) {
				debugger
				console.log(x + y + z);
				function D() {
					debugger
					console.log(z)
				}
				D()
			}
			return B;
		}
		let C = A(2);
		C(3);
	</script>
</body>

</html>